In the last year, substantive upgrades were performed on all systems in the Laboratory of Cellular and Molecular Biology Microscopy Core, including the total replacement of our Zeiss 510 Laser Scanning Confocal Microscope with a state-of the-art Leica SP8 Laser Scanning Confocal Microscope with a white light laser for excitation. 30 researchers used the resources of the Laboratory of Cellular and Molecular Biology Microscopy Core. While most of the researchers come from the Laboratory of Cellular and Molecular Biology, the Core has been used by scientists from the Laboratory of Immune Cell Biology, the Section on Cellular and Developmental Biology at the National Institute of Child Health and Human Development, the Genetic Disease Research Branch and The University of Maryland Department of Physics. Almost all of the Principal Investigators in the Laboratory of Cellular and Molecular Biology have projects that involve the Core facility. Dr. Lawrence Samelson uses Core resources for the project Biochemical Basis of T Cell Activation. Dr. Carole Parent's projects, Signaling Events Regulating Chemotaxis and Chemotactic Signals Regulating Human Neutrophil and Breast Metastatic Migration use Core instruments. Dr. Paul Randazzo has made extensive use of the Core for the projects Regulation of focal adhesions and Turnover of invadopodia. Dr. Ying Zhang uses Core instruments for the project Molecular Mechanisms of TGF-beta Signaling Pathway. The Core has been involved with the project Cbl Proteins as Regulators of Tyrosine Kinase Signaling from Dr. Stanley Lipkowitz, who is now Chief of the Women's Malignancies Branch. .In addition, the Core facility has been used by personnel working with Principal Investigators from other groups including work with Dr. Paul Love on the role of the protein Themis in T cell activation Dr. Jonathan Ashwell on the role of ZAP-70 in T cell activation. This research usually involves the use of a Leica SP8 Laser Scanning Confocal Microscope or a PerkinElmer UltraView Spinning Disk Confocal Microscope, with some usage of our Total Internal Reflection Fluorescence (TIRF) microscope. Most of the users view immunofluorescent staining on fixed samples with the Leica LSCM while the spinning disk confocal is generally used for live cell imaging. The TIRF system is also being used for the projects Regulation of focal adhesions and Turnover of invadopodia with Dr. Paul Randazzo. We routinely use our TIRF microscope for PhotoActivation Localization Microscopy (PALM) and Stochastic Optical Reconstruction Microscopy (STORM). These high resolution techniques allow us to determine the location of single proteins clustered in signaling complexes in T cells with an accuracy of around 20 nm, well below the diffraction limit of visible light. We can now perform two color PALM imaging and multi-color STORM imaging.